The present invention relates to a bicycle having a two wheel drive arrangement, in which both the front wheel and rear wheel are driven simultaneously and independently when the pedal crank is rotated.
When riding a bicycle on difficult terrain, it would be advantageous to have an independently driven front wheel, which could assist in providing a gripping force to compensate for any slip that may occur with the driven rear wheel. The advantages of all wheel drive are well known with respect to automobiles.
In designing a front wheel drive system, there are two principal challenges that are not present on a standard rear wheel only drive bicycle. These challenges arise from the fact that the front wheel of the bicycle must be free to turn. Thus, a system must be designed in which the chain driving the front wheel can operate without interfering with the turning of the front wheel. Furthermore, the presence of a chain system on the turning front wheel, results in a changing of the tension of the front wheel drive chain as the wheel is turned.
Thus, it is an object of the invention to provide a front wheel drive system in which the front wheel is free to turn without interference from the front wheel drive chain.
It is a further object of the invention to provide a front wheel drive system having a self-compensating means for maintaining a constant and proper tension on the front wheel drive chain as the front wheel is turned.